Editors. "John Zapolya is crowned King of Hungary". The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14371, accessed 23 May 2013.]
John Zapolya is crowned King of Hungary, ruling until his death in 1540. Throughout his reign, however, his position is to be placed under constant attack by Archduke Ferdinand of Austria's rival claim to the throne.